1. Technical Field
This invention is related to the field of replicating pattern designs onto a surface, and more particularly to semiconductor mask works.
2. Discussion
In the field of semiconductor design, intricate patterns are constructed of conductive and non-conductive materials on top of a flat surface, such as a silicon wafer, or, in the case of mask making, on a piece of glass. To fabricate a semiconductor pattern, or mask, using Electron beam (commonly called "E-beam") lithography, a surface is coated with a thin layer of material, such as a metal, and then coated with an electron sensitive resist on top of the metal. A finely positioned electron beam is then used to draw the pattern on the resist. The molecular structure of the resist is altered in those areas where the electron beam is applied, while the remaining areas of the resist are unaffected. Once the pattern has been "drawn" by the E-beam, a developer is applied to the surface. The developer dissolves the resist in areas which were not exposed to the Electron beam, and an etching chemical is used to eat away the metal which lays beneath the now dissolved resist. In this way, the desired pattern is "sculptured" into the metal. Another chemical may then be used to remove the E-beam treated resist, leaving behind only the metal pattern.
Generally, a semi-conductor design has several layers, each requiring its own unique pattern.
One limitation in the design and production of semiconductor circuits lies in the ability to accurately reproduce patterns onto the resist. A complex pattern having intricate details becomes more difficult to reproduce due to inherent limitations in E-beam resolution. Thus, as patterns become smaller and smaller in order to produce more densely packed and smaller semiconductor chips, it becomes imperative to insure that the pattern does not have areas whose details are too fine to allow proper reproduction.
It would therefore be advantageous to provide a method for interrogating patterns and optimizing patterns prior to their use in semiconductor production so as to eliminate areas of the pattern which are too fine to allow proper replication during the semiconductor production process. It would be further advantageous if this method were automated to increase accuracy and speed of the optimization process. It would be further advantageous if such a method were able to optimize the pattern using as few iterations as possible.